# frozen_string_literal: true

# This file implements a simple consistency test for Redis-rb (or any other
# Redis environment if you pass a different client object) where a client
# writes to the database using INCR in order to increment keys, but actively
# remember the value the key should have. Before every write a read is performed
# to check if the value in the database matches the value expected.
#
# In this way this program can check for lost writes, or acknowledged writes
# that were executed.
#
# Copyright (C) 2013-2014 Salvatore Sanfilippo <antirez@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

require 'redis'

class ConsistencyTester
  def initialize(redis)
    @r = redis
    @working_set = 10_000
    @keyspace = 100_000
    @writes = 0
    @reads = 0
    @failed_writes = 0
    @failed_reads = 0
    @lost_writes = 0
    @not_ack_writes = 0
    @delay = 0
    @cached = {} # We take our view of data stored in the DB.
    @prefix = [Process.pid.to_s, Time.now.usec, @r.object_id, ""].join("|")
    @errtime = {}
  end

  def genkey
    # Write more often to a small subset of keys
    ks = rand > 0.5 ? @keyspace : @working_set
    "#{@prefix}key_#{rand(ks)}"
  end

  def check_consistency(key, value)
    expected = @cached[key]
    return unless expected # We lack info about previous state.

    if expected > value
      @lost_writes += expected - value
    elsif expected < value
      @not_ack_writes += value - expected
    end
  end

  def puterr(msg)
    puts msg if !@errtime[msg] || Time.now.to_i != @errtime[msg]
    @errtime[msg] = Time.now.to_i
  end

  def test
    last_report = Time.now.to_i
    loop do
      # Read
      key = genkey
      begin
        val = @r.get(key)
        check_consistency(key, val.to_i)
        @reads += 1
      rescue => e
        puterr "Reading: #{e.class}: #{e.message} (#{e.backtrace.first})"
        @failed_reads += 1
      end

      # Write
      begin
        @cached[key] = @r.incr(key).to_i
        @writes += 1
      rescue => e
        puterr "Writing: #{e.class}: #{e.message} (#{e.backtrace.first})"
        @failed_writes += 1
      end

      # Report
      sleep @delay
      next unless Time.now.to_i != last_report

      report = "#{@reads} R (#{@failed_reads} err) | " \
               "#{@writes} W (#{@failed_writes} err) | "
      report += "#{@lost_writes} lost | " if @lost_writes > 0
      report += "#{@not_ack_writes} noack | " if @not_ack_writes > 0
      last_report = Time.now.to_i
      puts report
    end
  end
end

SENTINELS = [{ host: "127.0.0.1", port: 26_379 },
             { host: "127.0.0.1", port: 26_380 }].freeze
r = Redis.new(url: "redis://master1", sentinels: SENTINELS, role: :master)
tester = ConsistencyTester.new(r)
tester.test
